Safety switch



Jan. 7, 1936.

G. D. BROWN ET AL SAFETY SWITCH Filed March l, 1934 jim" J2 24 Patented Jan. 7, 1936 i UNITED STATES PATENT OFFICE SAFETY SWITCH George D. Brown and George M. Myers,

Nanty Glo, Pa. A

Application March 1, 1934, Serial No. 713,594

2 Claims. (Cl. 20G-2) This invention relates to switches and more base I5 held against movement within the casparticularly to a safety switch adapted for use in ing Il) by means of a bolt |8 which holds the mine explosive operations. device in assembled condition within the cas- An object of this invention is to provide a ing l0. The guides |6 are adapted to engage and 5 switch which is adapted to be interposed in a guide slide bars I9 which are connected at one end 5 power circuit and connected to a fuse or detonaas by a connecting bar 2li. tor, the switch being so constructed that the pow- An upstanding or right angularly related bar er circuit will be closed and grounded when the 2| is secured at its lower end to the connecting switch is in its normal position and the circuit bar 20 and a draw bar 22 is connected at one end 10 to the detonator will be closed and grounded. to this post or upstanding member 2| and slidably 10 Another object of this invention is to provide extends through One end Wall 0f the housing l0, an improved switch of this kind wherein the opand is provided at its outer end with an eye 23. erating members of the switch will be thoroughly A connecting bar 24 is disposed between the slide insulated so that the switch can be connected to bars I9 intermediate the ends thereof and is prefflexible conductors and carried to the desired erably of insulating material and holds these bars 15 point where it may be set up and connected to I9 in spaced parallel relation to each other coactthe detonator by additional conductors. ing with the end member in holding these bars A further object of this invention is to provide |9 so that they will freely slide in the guide a switch which is so constructed that there will members I6. A contracting spring is secured 20 not be a premature or accidental discharge of at one end to the end of the housing opposite from 2 the fuse or detonator by reason of the interruption the draw bar 22 and the opposite end of the spring of contacts due to the space between the con- 25 is secured to the upstanding post or bar 2|. tact springs, terminals and ground bar when the In this manner, the slide comprising the members switch is in its normal position. |9, 20 and 24 will be constantly urged toward one 25 The above and various other objects and adend of the housing I8, the purpose for which will 25 vantages of this invention will in part be described be hereinafter described. and in part be understood from the following de- A conductor 26 extends through one end of the tailed description of the present preferred emhousing I0 'and is connected at one end to a bodiment, the same being illustrated in the accontact post 21. A second conductor 28 is extend- 30 companying drawing whereinzed through this wall of the housing I0 and con- Figure 1 is a detail top plan view of a device nected to a second fixed contact post 29. These constructed according to the embodiment of this conductors 26 and 28 are conected at their oppoinvention with the top removed. site ends to a source of current supply and con- Figure 2 is a transverse sectional View taken stitute power conductors.

substantially on the line 2-2 of Figure 1 and A bridging element 01 ground bar 3U iS Secured showing the cover in position. to the end bar 20 and is adapted to bridge the Figure 3 is a diagrammatic view of the circuits space between the two contact posts or terminals within which the switch hereinafter described is 2l and 29 so that when the switch is in its normal interposed, or inoperative position, the power circuit com- Referring to the drawing wherein like numerals prsing the conductors 26 and 28 will be closed 40 designate corresponding parts throughout the Or'grOllnded. views, the numeral III designates generally a cas- A conductor 3| is connected at one end to a ing 0f Substantially rectangular Configuration terminal O1' flXed post 32 and another COIldlICDI provided with an open top which is adapted to be 33 is connected to another terminal -or xed post closed by means of a cover or lid hinged at one 34 which is spaced from the terminal 32, and end by means of hinges I3. The housing or box each of these terminals, as well as the terminals ID is provided with outwardly extending flanges 2'I and 29, are mounted on the base I5 within the l2 at each end, each having an aperture I4 therehousing I0. The terminals 32 and 34 are posithrough so that the housing may be mounted on tioned forwardly of the connecting bar 24 and a a suitable support. An insulating block or base metal contact 35 of relatively resilient construc- |5 is positioned within the box l0 and engages tion is secured to the side of the connecting bar the bottom of the box I0. A pair of guide mem- 24 confronting the terminals 32 and 34. The bers I6 constructed in the form of rectangular conductors 3| and 33 have their opposite ends loops are secured as by a plate II to the base I5. connected to a detonator 36 which is shown dia.-

The plate I1 is attached to the base I5, and this grammatically in Fig. 3, and which is adapted to u 2 aoaaeea light an explosive 31 also shown diagrammatically. By providing the two closed circuitshereinbefore described, there is no possibility of accidental discharge of the detonator 36 while the Workmen. are preparing the explosive 3l.

A resilient and movable contact 38 is secured to one of the slide bars I9 and a second resilient and movable contact 39 is securedvto the other of the slide bars I9 and disposed in forwardly offset relation to the two terminals 32 and 34. The movable contact 38 confronts the terminal 32 andthe movable contact 39 confronts the terminal 38. y A conductor or connecting wire 40 connects the contact 38 with the terminal post 21 and a con l position, which is the normal position of the slide, the contacts 38 and 39 will be positioned forwardly and in spaced relation to the terminals 32 and 34. By reason of the grounding of the current in the conductors 26 and 28, therewill be no jumpingv of current from the .contact 38 to .the terminal 32 or from the contact 39 to therterminal 34. In this positionalsd, the bridging member 35 connects the tw'o terminals 32 and 34. When it is desired to set oil the detonator 36,v the draw bar 22 is pulled, which opens the circuit comprising the conductors 26 and 28'and the current will then flow from the terminal 26 through the terminal '48 and the contact 39 to the terminal 32 and then through the conductor 3| to the detonator. The current will pass on its return from the detonator through the conductor 33 to the terminal 34, contact-39,conductor'4|, terminal 29 and conductor 28. It is, ofcourse, understood that the direction of the flow of the current may be in either direction and the above description is merely for purposes of showing the connection between the power circuit and the detonator circuit.

Itis, of course, understood that various changes and modifications maybe made inthe details of construction and design of the above speciiically described embodiment of this invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claims.

bridging member carried by said slide member, a.

spring constantly urgingsaid slide member in a position whereby said bridging member will engage said terminals, a second pair of terminals carried by the base in spaced relation tdsaid rst l pairof terminals, a second bridging membercar-a ried by said slide member in spaced relation t0 said iirst bridging member and engageable with said second pairof terminals when said rst bridging member engages said rst; pair of terl minals, a pair of4 contacts secured to said slide member and adapted to engage said second pair of terminals-when said slide member has been moved tondisengage eachvof said bridging members from each pairs-of terminals, and flexible conductors .connecting said first pair of terminals with said contacts.I

2. A safety switch, Vcomprising an insulated base, a slide member comprising a pair of parallel bars connected together at one end, Aguide means engaging the-` parallel bars for 'slidably mounting said slide; member on the base, a' of terminalssecured to the base between said parallel bars and adapted to be connected to a `source of electric power supply, a terminal bridging member extending -between the-parallel -bars and engageable with the terminals, a spring constantly. urging said slide member in a position whereby said bridgingmember will engage said terminals, a second pair of terminals disposedV 3; between said parallel bars intermediate the ends thereof and in spaced relation to said rst pair .0f terminala a transversely extending bar connecting said f parallel bars intermediate the ends thereof, a'bridging member on said connecting 4g bar engageable AWirth said second vpair of ter'- minals when said rst bridging member engages said ilr'st pair of terminals, a pair of confronting contacts secured to the inner sides of said parallel bars and normally disposed in spaced relation to said second pairof terminals, and conductors lconnecting saidcontacts with said iirst pair of terminals, said contacts engaging said second pair of terminals when said slide member is moved to disengage each of said bridging mernv bers from said pairs of terminals.

GEORGE D. BROWN. GEORGE M. MYERS. 

